Abstract
Background: Increased contact stress with a femoral resurfacing prosthesis implanted in the medial femoral condyle and a non-functional meniscus is of concern for potential deleterious effects on tibiofemoral contact mechanics.
Methods: Peak contact pressures were determined in seven fresh frozen human cadaveric specimens using a pressure sensitive sensor placed in the medial compartment above the menisci. A knee simulator was used to test each knee in static stance positions (5°/15°/30°/45°) and through 10 dynamic knee-flexion cycles (5°–45°) with single body weight ground reaction force (GRF) which was adjusted to the living body weight of the cadaver donor. All specimens were tested in three different conditions: Untreated knee (A); Flush implantation of a 20mm resurfacing prosthesis (HemiCAP®) in the weight bearing area of the medial femoral condyle (B); Complete radial tear at the posterior horn of the medial meniscus with the femoral resurfacing device in place (C).
Results: On average, flush device implantation resulted in no statistically significant differences when compared to the untreated normal knee. The meniscal tear resulted in a significant increase of the mean maximum peak contact pressures by 63%, 57%, and 57% (all P ≤ 0.05) at 15°, 30° and 45° static stance positions and 78% (P ≤ 0.05) through the dynamic knee flexion cycle. No significant different maximum peak contact pressures were observed at 5° stance position.
Conclusion: Possible effects of reduced meniscal tissue and biomechanical integrity of the meniscus must be considered in an in-vivo application of the resurfacing device.
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